Water antenna



Jan 6, 1959 N. E. LINDENBLAD 6 WATER ANTENNA Y Filed Nov. 2, 1953 WWII/Mi V- 1 INVENTOR.

Nns E. LINDENB'LHD ATTORNEY Patented 2867862 Umted States Patent G we 4 1 a I 3 a ,naaaieaesanea i6 give it entrant antenna for high frequencies;

1, Fig.5 show inhor iz'ontal section',"an aiiniflai' 2,867,802 form omnidirectional radijatidn; and

F igg a is ape rs" ec'tive view of the r 7 WATER ANTENNA Referring a at; and r I ,provi e; l cFe-cLlll lei b ifi'll ee t iifia Jeass Refit-lie d Qm 't' w i hl Corporation of America, a corporation of Delaware die for example of wood or plastic,

n win pencils of It maybe in Application November 2, 1953; serial-Na. 389,527 aype 999W .9 9 12 claims. or. ea-1a,

hal t awar -heft. 6 .b depth is half its length, afn'd its thickne ressih'an its" depth. Forexai'nple, Ina frequ cy This invention relates to antennasiand more 15 1,000 k ycles' itwould be almos' 50,, feet long,

larly to antennas formed in the surface of a body of d s'llbrffrgea delgth 51551630111311? 250' feet, 5115 mll h: t V ma ler. t c cra q .1, 1 ,0 m lcy l It is an object of myinvention to devise an antenna nrdpea little under1 .5; f eet,long,.of about 2 feet formed in the surface of a body of water. Further .ob- Submerged delzi h tind .of any thickness less ihan, 2 /2: jects are to provide simple and practical means of vso e S o e j il ep ihch s As shown in' .Fig s. 1 and forming slot} antennas, and to provide antennas giving 1 b lj W P X,} e ht d 1,19 nd hi -1& desired radiation patterns. I a in place by piles 11 The box could b e fr'eely floating, ;S lot,antennas formed in metal are known. In the a i e btegi t' t weii a h .thaI-II; l pp j e y P case of.a sheet of metal constituting a plane conductive Cqn u t q i e f p h s1'2. Ba e P Yi e surface -provision of an open slotscan form an antenna. ppos t p tc QeS P din Qi t With and con Itis also known to provide a backingshell, which gives duction to th We L d 14 1 1 onfieetft e P he an open s'lot backed by a cavity With conductive wall to a g ali al cahle l6 which leads to a transmittei orre surfaces. When leads of opposite polarity. are connected ceiveij, not shown. Aseal 1 7 is provide where the cab le at the opposite sides of the slot or of the backing cavity, P thro'llg th hex W l, n 5, f m, 25 i h and radio frequency alternating current is applied; radia qt ler h ub erged p r tiphsof walls could be all tion takes place from the. opposite edges of the slot; ois c m alifde i ed instead of haying small conduc; The strongest radiation fields us'u'ally extend transverse ivea e i n q d h .a d e .eq .r. v t is... q ed to the direction of the slot. Desirably the slot should be by rwn-cQnductiVe wlid or air space.- abouta half wave-length long; The backing cavity The conductiv ar as, o pat hes 1}, 13 should be lgshoirld be about a" quarter wave-length deep, and less e e agh tama fihei ed of the antenna than a' quarter wave-length wide. Slot antennas could l of e,tiane ,li asab U therefore range from very large structures for low fre- Fi illustrates my invention incorporated in. a quencies; which have long wave lengths, to very small Pneumatic life Yaft- Here I have I WIJ. atpoftion O a structures for high frequencies, which have short wave fe, 0, ving tu e 20 and bottom 20b. On the lefigtlis'; 40 under side pf thepneumatic tube is formed a down The characteristics of slot antennas and their dime'nwar ly e t n n pou f i n n like t sional variations are known in the-art. See for example embodiment, m y twice. as long S is p; and.

Slot Antennas by Nils E. Lindenblad in the Proceedh n hi P 11016 2 HII th pouch to ings of the IRE of December 1947, and Antennas by e tended bvair P essure When the tube is inflated.- John D. Kraus, McGrawHill Book Co., Inc, New York, OH, th put t I f the P h 21 are P F I N. Y 1950, 353-381, conductive areas or patches 22, 23 connected by leads My i e ti i l using th surface of a b d f 2jl, 25 through'cable'26 to a radio transmitter ornreceiver, water, such as the mean or a lake, for the plane conductno ho n, Which may be located on the raft. The Water snrraeeer a slot antenna, and forming the slot at the round, this displacing pouch forms in effect a slot surface of th e' water and its backing cavity in the Body 5 antenna. of the water by displacement with a suitably shaped .412 Pia--31 have Shown a p t floating bodyrwhich dielectricbpdy. The provision of thedielectric discon- Wi P d a Slet' aniennain the Watefl A11 elongated tinuity in the water to form a slot antenna is embraced balloon 30 0f hour-glass cross-Section has a p float in my invention, as is also the means for displacing the Portion 30a and a bottom displacement Portion A water to form an antenna. Salt water is best adapted for rigid yo e forming a long, narrow 1 p, holds the use of my invention, but most bodies of fresh water have Slot dimension When inflated through Valve 37 and suflicient conductivity for the purpose. with a suitable weight 39 in the bottom, it will float with I th d i its waist just below the surface. In this form, as is pos- Fig, 1 is a perspective View of an antenna formed in sible in the others, the backing cavity is thicker than the the surface of a body of water, by for example a large Width of the slot. As known in the art, this has radia- Wooden box suitably supported in partially submerged tion characteristics which are preferable for some puro ition, as b ile d i i the b tto f a lak poses. Here again, conductive areas 32, 33 provide con- Fig, 1a is a cross-section of same viewed in the directact With the sea water at the OPPO-Sltfl sides Of the cavity. tion of the ow A i Fig 1; While this antenna might be externally fed as in the Fig. 2 is a sectional view of the end portion of a other embodiments, it y be designed as a Self-C011- pneumatic life raft incorporating an antenna in accordtflined radiator, for use as a floating beacon for p ance with my invention; For such use I have shown the submersion weight as Fig. 2a is an elevation of same; batteries 39, connected to a radio frequency oscillator 38 Fig. 3 shows, in section, an inflatable floating device which is connected by leads 34, 35 to the conductive forming a sea-water slot antenna; areas. The oscillator, indicated by block 38, may be Fig. 3a is an elevation of same; physicallymounted in any convenient manner Within the displacement portion, and may be switched on by any desired switch-throwing expedient.

Fig. 4 illustrates a simple way of providing a slot antenna for higher frequencies. Here a wide, thin paddle 40 of wood or other dielectric, with handle 40a and blade 40b, has conductive areas 42, 43 on opposite sides of the blade. These are connected by leads 44, 45 and cable 46 to a radio transmitter or receiver. Immersing the paddle to a depth about half its width, with the conductive patches submerged, provides a slot antenna.

In Figs. and 5a I have illustrated my invention embodied in an annular form to give an omnidirectional radiation pattern. Here acylindrical ring 50 of plastic or other dielectric material is partially submerged in the water. Its outside diameter may desirably be one half wave length, its top projects above the surface to keep the ring slot open, while its specific gravity is sochosen as to give it a depth of immersion of one quarter wave length, and its shell thickness is less than a quarter wave length.

Exterior conductive areas or patches 52, approximately 120 apart, and corresponding interior conductive patches 53 approximately 120 apart, are fastened to the surfaces of the cylindrical ring and are in directcontact with the water outside the ring and inside thering respectively. The outside surface patches 52 are fed by one set of inner leads 54, which join to become the inner conductor of a coaxial cable 56. The inside surface patches 53 are fed by a set of leads 55 which may constitute outer conductors around leads 54. These join to become the common outer conductor of a coaxial cable 56. In all cases, lines other than coaxial cables maybe used if permitted by the frequencies being employed.

Other antenna configurations may be provided to give desired radiation patterns and to suit the wave lengths employed and conditions of use. Such antennas may 'be used wherever suitable. They have advantages for example for emergency life-boat use, for use as a float from a submerged submarine, and for use wherever a body of water is available and construction of elevated structures or metal structures is difficult or undesirable.

What is claimed is: 1

1. A slot antenna for radiating or receiving radio frequency energy propagated through the air and utilizing a body of water as aconductive medium, comprising, a dielectric body partially immersed in the body of water to form a non-conductive cavity extending down into the water from the surface thereof, and antenna leads conductively coupled to the water at opposite sides of the dielectric body.

2. A slot antenna as defined in claim 1 wherein said dielectric body has length and thickness in the horizontal plane, and is immersed in the water to a depth intermediate said length and said thickness.

3. A slot antenna as defined in claim 1 wherein said antenna leads are conductively coupled to the Water thru 4 conductive patches on the opposite sides of said dielectric body.

4. A slot antenna as defined in claim 1 wherein said dielectric body has a smaller cross-sectional area at the surface of the water than it has below the surface.

5. A slot antenna as defined in claim 1, and in addition, a power supply and a radio frequency oscillator mounted Within said dielectric body, and output leads coupled between the output of said oscillator and said antenna leads.

6. A slot antenna as defined in claim 1 wherein said dielectric body includes an enlarged inflated portion floating on the surface of the water.

7. A slot antenna as defined in claim l wherein said dielectric body is shaped as a paddle.

8. A slot antenna as defined in claim 1 wherein said dielectric body is annular, and said antenna leads are conductively coupled to the water at the inner and outer sides of said body. I

9. A slot antenna as defined in claim 1 wherein the crosssectional area of said dielectric body at the surface of the water is elongated and has a length substantially equal to a half-wavelength at the operating frequency of the antenna. Y

10. A slot antenna for radiating or receiving radio frequency energy propagated through the air'and utilizing a body-of water as a conductive-medium, comprising, a hollow dielectric body partially immersed in the body of water to form a non-conductive cavity extending down into the water from the surface thereof, and antenna leads conductively coupled to the water at opposite sides of the dielectric body. p

11. A slot antenna comprising a body of conductive fluid having therein a dielectric'space to form a slot at the surface of said fluid, and a pair of antenna leads positioned at opposite sides of said space to electrically contact said fluid. 12. A slot antenna for radiating or receiving a radio frequency signal through the air andadapted-to utilize a body of water as a conductive medium, comprising a dielectric body adapted to be at least partially immersed in said body'of water to form a non-conductive cavity extending down into said water from the surface thereof, electrodes on opposite sides of said dielectric body for contacting said water, and leads coupled to said electrodes for applying thereto or deriving therefrom a radio frequency signal.

References Cited in the file of this patent UNITED STATES PAT ENTS' 

